(1) Field of the Invention
The present invention pertains to systems, apparatus, and methods for managing an isolation environment, such as those in a collective protection shelter, particularly to controllers that are adaptable in their scope of operation, and incorporate environmental and process sensors and diagnostic and prognostic algorithms to ensure the operational integrity of the isolation environment.
(2) Background of the Invention
In recent years the need to protect individuals from dangerous substances in the air has become one of increasing interest. All human beings must breath and the introduction of harmful airborne agents into the air they inhale creates a dangerous situation whereby individuals can be injured or even killed and which can strain the emergency response capability of a populated area. While all environmental air contains some impurities which can harm those breathing it, such as cold viruses and allergens, recent developments in conventional warfare and terrorism, have resulted in an increased likelihood of large scale contamination of air wherein venues that offer physical protection and sources of clean air are highly desirable to prevent catastrophic outcomes.
The danger of a nuclear, biological, chemical or radiological (NBCR) weapon being unleashed on military forces, or on civilian centers, is a nightmare scenario for many government organizations. Such an attack can stymie military effectiveness, or bring day to day economic activity to a grinding halt. Even without the purposeful use of nuclear, biological, chemical or radiological weapons, the possibility of industrial accidents involving such agents in populated areas is also a danger and governments must be able to respond to protect the citizenry.
Particularly in military or emergency situations where contamination occurs as the result of a purposeful attack, it is necessary that personnel be able to continue to carry out tasks such as military response, policing, and medical care even while the environment is contaminated. Further, scientific analysis and cleanup activities need to be performed to help clean the contaminated environment. Traditionally, when operating in a contaminated environment, personnel will utilize protective garments which allow them to act fairly autonomously to perform such tasks. In many situations, however, the task is inconsistent with the use of protective garments. For instance, delicate surgical activities can generally not be performed as the garments are too bulky to allow fine motor activities.
To prevent exposure to contaminants and provide for a location both where individuals can escape from the contaminants, and can perform tasks to which cumbersome protective garments are not well suited, an isolation environment, such as that inside a collective protection shelter, is generally used. A collective protection shelter is, in effect, a self-contained building having a supply of clean air and able to house multiple individuals which can carry on activities within the structure. So as to provide clean air, environmentally contaminated air is generally pulled into an air handling device, filtered to remove the contamination, and the clean air is pumped into the structure housing the individuals. The structure is simultaneously pressurized to seal it, thus preventing leaks from the outside environment.
Isolation environments may be permanent or may be temporary. In emergency responses or military field activities, a temporary structure is generally preferred as it can be quickly setup anywhere when needed, and more easily stored when not needed. Often the temporary structure is inflatable whereby the structure can be setup in the zone of contamination and can then be filled with clean air using a portable filtration system, some of the air being used to provide structural support. Inflatable structures are generally fairly easy to transport and erect, and they readily collapse when not in use.
While inflatable structures of this type can be very useful in military and emergency situations, they do require some level of effort to maintain in operation once erected. In particular, airflow into the structure must be maintained in order to maintain inflation. If air flow is insufficient, the structure can collapse or can draw in unfiltered external air which can contaminate the isolation environment. Those inside the structure need to be able to monitor the structure and the environmental control unit over time and perform any needed maintenance actions before a failure occurs which could result in the occupants being exposed to contaminants. Further, monitoring of the internal environment is necessary to keep the occupants comfortable and in a safe and usable environment.
There are generally two ways to deal with maintenance, the simplest is to simply wait for a failure, and then repair or replace the component which has failed. This is generally referred to as corrective maintenance (CM). While CM provides for the most cost effective use of components as no component is replaced before it has completely exhausted its useful life, it is generally not practicable in an isolation environment as the occurrence of failure may result in contamination and loss of the isolation environment.
Instead, in order to operate effectively, an isolation environment will need to be able to estimate when a component will fail, and replace it just prior to its failure to maintain the operational integrity of the isolation environment. This is commonly called preventive maintenance (PM). While effective PM can provide continuous safe operation of the collective protection shelter, it also imposes its own costs. Currently, there is no mechanism to determine the useful life remaining in components in a collective protection shelter other than simply the time they have been in use. Therefore, shelters use what is called time-based maintenance (TBM).
TBM relies on prior operational tests of components under particular conditions and determines when they are likely to fail. TBM then uses this time estimate to determine when maintenance should occur by simply setting the maintenance interval to be less than the time for the component to fail. In this way, the system should, theoretically, never fail as no device ever reaches the end of its useful life.
The problem with TBM, is that TBM does not take into account actual operational conditions which generally will affect the operational life of a component. For instance, a filter may remain in service for a period of time longer than TBM dictates if it has not had anything to actually filter out, or a motor may last longer if it has been run at a more optimized speed, rather than at a maximum speed. Further, TBM does not necessarily know if a particular component may be more prone to failure due to an error in construction, or to changing conditions. TBM can try to statistically accommodate such diversity, but often, it is simply not possible to have enough exemplars to either recognize or to cope with all possibilities.
Generally, therefore, protocol dictates that devices be maintained more frequently than may be needed to prevent any unanticipated failures. While this can usually prevent failure, often, these maintenance procedures entail risk themselves. Personnel may be required to leave the protected environment or temporarily shut off various components to perform the needed maintenance. Each of these represents an opportunity for unintended contamination. Therefore, while TBM is designed to minimize danger from failure, it opens up an avenue for danger from the practice of unnecessary maintenance. Further, for disposable goods, such as air filters, the TBM can impose additional costs. Replacing filters before required means that more filters are needed in storage to keep the shelter operational. As transport and provision of filters uses logistical resources which may be better used for different purposes, the inefficient use of disposables such as filters may be inadvertently wasting resources needed elsewhere.
In order to deal with the problems of TBM, it is desirable to instead utilize condition-based maintenance (CBM). In CBM the condition of the device is directly monitored, or various other conditions which may be indicative of the performance of a device are monitored. Both of these readings are generally taken over time. A failure rarely occurs suddenly, but a component will generally curve toward a failure over time until the condition finally crosses a threshold where failure occurs (or could occur at any time). With CBM, as the device approaches the threshold, maintenance is performed just in time. In this way, the actual expected failure based on the actual performance and current conditions is used, instead of the theoretical failure based purely on time.
CBM, while more efficient, particularly with regard to disposable goods, generally requires a mathematical analysis of historical events and trends in a measurement and significantly more data than TBM. The behavior of a device over time is generally much more indicative of future performance (and possible failure) than a behavior snapshot taken at any given point in time. For instance, a motor which has been exposed to many stops and starts is likely to need maintenance sooner than one which has been continuously running for the same time, even though both may show the same electrical current input measurement.
The current state of the art in the design of controllers for collective protection shelters is based on the use of electromechanical relays, diodes, pushbutton and rotary switches, and enunciators to monitor and control the operation of the shelter. The resulting system architecture is inherently inflexible to changes due to its hard-wired nature. It also does not offer the functionality needed to store and mathematically analyze data from multiple sensors, or present it in a variety of formats where a trend may be apparent. Finally, the designs are unable to provide diagnostic or prognostic data and are instead limited to a situational notification role. In particular, a series of alarms indicate that a particular situation has occurred and a series of controls allow the user to alter some facet of the operation without regard for each other.
Also, current controllers, due to their hard-wired nature, are designed to operate with specific sensors. If those sensors become obsolete, replacing them with better models may not be feasible or requires an enormous amount of work which does not allow for the rapid upgrade of the shelters as better sensors become available. The same holds true of upgrades to the power source used to operate the shelter, e.g., going from hydraulic power to electrical power.